WALTHAM – Boston Celtics star Paul Pierce showed up for his pre-practice meeting with reporters carrying a basketball, which he bounced from time to time while answering questions.

Get used to it: Pierce will have the ball in his hands a lot more from now on.

Two days after learning Rajon Rondo has a torn knee ligament that will keep him out the rest of the season, the Celtics returned to practice for the first time to work on an extended future without the All-Star point guard. Pierce is the most likely player to handle the ball at key points in the game, but coach Doc Rivers says everyone will have to work to replace Rondo.

“It’s just basketball,” he said. “There’s no point guard. It’s just basketball by committee. I don’t want a guy thinking now he’s Rondo.”

Rondo was averaging 13.7 points, 11.1 assists and 5.6 rebounds per game, with triple-doubles in back-to-back games when he was scratched Sunday against the defending NBA-champion Miami Heat. He was sent to the hospital to check on what the team believed was a hyperextended right knee.

The actual diagnosis: A torn anterior cruciate ligament that required surgery and a recovery period of up to a year.

“Everybody was in a fog almost,” center Kevin Garnett said at the team’s workout facility. “I think it’s kind of settling in and I think everybody is trying to put their arms around the concept that he’s actually hurt, hurt to the point where he can’t play. That’s what had everybody in a fog, even him.

“He came in this morning, and seeing him in there was kind of unreal. The fact that it is real, everybody is going to consolidate and pick up the pieces and try to carry this thing.”

Rondo was injured in a double-overtime loss to Atlanta on Friday night, a game in which the Celtics blew a 27-point lead. Despite playing without their floor leader Sunday – players didn’t know the extent of the injury until after the game – they beat the Heat in double overtime to improve to 21-23 and hold onto a 2½-game lead over Philadelphia for the eighth and final playoff spot in the East.

They are back at TD Garden Wednesday night against the Sacramento Kings. Rivers said he isn’t sure who will bring the ball up the court – it will probably change from game to game depending on what the opponent is doing – but once the offense is set up, he will expect everyone to be involved.

That’s the way the Celtics played Sunday.

Now they need to do it the rest of the season.

“It’s a no-point-guard system,” Rivers said, noting his second unit has been playing that way all season. “Now the entire team needs to do it. We have a lot of guards. We just don’t have a lot of point guards.”

Rivers said Courtney Lee, who has been averaging 7.2 points and 1.4 assists in 22 minutes, will start for now. Leandro Barbosa, Avery Bradley, Jeff Green and Jason Terry will also have the ball more without Rondo on the floor.

“I don’t know if that’s a role I’m going to have,” said Barbosa, who backed up Steve Nash in Phoenix and is averaging 4.7 points and 1.2 rebounds in 11 minutes in his first season with the Celtics. “I’m not Rajon Rondo; I’m Leandro Barbosa. What I’m going to do is different for the team.

“I will do my best, but I’m not a point guard; I’m a shooting guard. I will do my best, but I’m not a Rajon Rondo.”

There is also the possibility general manager Danny Ainge would sign a player; former Celtic Keyon Dooling, who’s working for the team in community relations, has been mentioned as a possibility. The Celtics, who were already languishing below .500, could also trade one of their stars and begin rebuilding.